U.S. Pat. No. 3,760,049 to Borer et al discloses extruding a viscous solution or dispersion of soluble or dispersed metal compounds through a spinnerette; drawing the green fibers in hot air, preferably as a strand; collecting the strand in a free-form, relaxed manner on a moving belt which is continuously passed through a furnace to remove volatiles and burn off organic material; and continuously pulling the resulting refractory fibers in a straight or linear form through a furnace at a higher temperature to densify, strengthen, straighten and/or modify the microstructure of the fibers or develop desired crystalline species therein.
U.S. Pat. No. 3,846,527 to Winter et al discloses inorganic fibers produced by dry spinning a solution, sol or dispersion of one or more metal compounds which would not normally be spinnable but are rendered spinnable by inclusion of a small amount of a linear polymeric substance characterized by a degree of polymerization in excess of 2,000 and a concentration of 0.001 to 5 percent in the spinning dope.
European Patent Application No. 86105496.3 published 29.10.86 discloses a fabric for a printed circuit substrate composed essentially of inorganic fibers having a non-circular cross-section.
Japanese Patent Application No. 61 (1986) 139,217 filed June 17, 1986, discloses a method for producing quartz glass fiber comprising hydrolyzing a silicon alkoxide solution, forming a gel fiber, and baking the gel fiber in two steps: the primary baking carried out in an oxidizing atmosphere at a temperature lower than 600.degree. C. while applying a tension of 100 to 10,000 g/mm.sup.2, and the secondary baking at a temperature of 600.degree. to 1100.degree. C. while applying the aforementioned tension.
Japanese Application No. 61 (1986) 139,244 filed June 17, 1986, discloses production of silica fiber by sol-gel processing wherein the spinning liquor composed of silica sol further comprises a silicon compound of the general formula Y.sub.1 Y.sub.2 Y.sub.3 SiX wherein Y.sub.1, Y.sub.2 and Y.sub.3 are an alkyl group, allyl group or aryl group and X is hydrogen, chlorine, bromine, iodine or OR where R is an alkyl group with 1 to 10 carbons.
D. L. Segal discloses in "Sol-Gel Processing: Routes to Oxide Ceramics Using Colloidal Dispersions of Hydrous Oxides and Alkoxide Intermediates", Journal of Non-Crystalline Solids, 63 (1984) 183-191, that spheres may be formed from a hydrous oxide sol dispersed as liquid droplets in an immiscible organic solvent. In external gelation, removal of anion from the sol droplets by passing ammonia gas or adding a long-chain amine to the solvent results in gel formation.